Fuel injection nozzles for internal combustion engines



May 22, 1956 w, v01-|- 2,746,800

FUEL INJECTION NOZZLES FOR INTERNAL. COMBUSTION ENGINES Filed May 26, 1953 Lmwm United States Patent O FUEL INJECTION NOZZLES FOR INTERNA COMBUSTION ENGINES Willy Voit, Stuttgart, Germany, assignor to Robert Bosch G. m. b. H., Stuttgart, Germany Application May 26, 1953, Serial No. 357,407

Claims priority, application Germany June 17, 1952 2 Claims. (Cl. 299-107.6)

The invention relates to an improved fuel injection nozzle for internal combustion engines.

An object of the invention is to increase the output of the internal combustion engine by a suitable form of the stream of fuel and to lower the consumption of fuel thereof.

Starting from the known, fundamentally dierent forms of stream of pin nozzles and hole nozzles, it has proved to he the case that improvements can be obtained if, when injecting small amounts of fuel, that is to say in the region of no load and of light loadings, the form of the loose hollow stream is governed by a pin nozzle form and, when injecting large amounts of fuel, that is to say in the full load and upper load regions, the rigid wholly closed stream is governed by a hole nozzle form.

This is obtained in accordance with this invention by an injection nozzle whose nozzle needle contained in the nozzle member and on which the fuel pressure engages against the force of a closing spring, has on the end of the injection side a pin which is disposed with free spacing around it during the rst part of the needle opening stroke in a cylindrical injection aperture of at least 0.9 mm. diameter disposed in the nozzle member, but when the needle is completely raised, exposes the injection aperture to such an extent that the nozzle, which, during the rst part of the needle stroke works as a pin nozzle, acts as a hole nozzle when the needle is completely raised.

Apart from the known improvements in the internal combustion engine, smooth operation of the machine may be obtained in a conventional manner by the feature that, for obtaining a kind of preliminary injection, the injection nozzle is provided with such a stiff closing spring that the force of this spring increases, in the known manner, more powerfully during the iirst part of the needle stroke than the hydraulic opening force of the fuel engaging likewise on the needle but acting in opposition thereto, and which, after the raising of the needle, exerts an additional force in the opening direction on the needle owing to the needle shoulder surface becoming effective at the same time in addition to the raising shoulder.

The invention is further described with reference to the drawings showing three examples of construction, by way of example.

In the drawings:

Fig. l shows a longitudinal section through the first form of construction mounted in a nozzle holder,

Fig. 2 a part section on a larger scale through the rst form of construction, with the nozzle needle in the closed position,

Fig. 3 a similar View with the nozzle needle in the open position;

Fig. 4 shows a part section through the second form of construction, with the nozzle needle in the closed position,

Fig. 5 a similar view with the nozzle needle completely open;

Fig. 6 shows a part section through the third form of ICC construction with the nozzle needle in the closed position, and

Fig. 7 a similar view with the nozzle needle completely open.

ln the body 1 of an injection nozzle, a nozzle needle 2 is tightly guided, on which a closing spring 4 acts through a peg 3 in the known manner` The spring 4 is accommodated in a nozzle holder 5 on which the nozzle body 1 is secured by means of a screw cap 6. The fuel flows through a channel 7 in the nozzle holder and channel 8 in the nozzle body l towards an annular space 9 in the nozzle body.

The nozzle needle 2 with a diameter of D1 is reduced to the diameter D2 at the point where the nozzle needle lies on the seat 10 in the nozzle body. On the end of the nozzle needle a pin 11 is provided which lies with a certain spacing within the cylindrical injection aperture i2 arranged coaxially with the nozzle needle, until the nozzle needle is raised. The diameter of the cylindrica spray aperture 12 amounts at the most to 0.9 mm.

When the nozzle needle is closed, the fuel pressure engages on an annular shoulder of the nozzle needle, the dimensions of which are determined by the diameter D1 and D2 of the nozzle needle. After raising the nozzle needle from its seat l0 in the nozzle body, an additional needle shoulder becomes effective in known manner, on which the fuel presses likewise in the opening direction. The dimensions of the additional needle shoulder are determined by the diameter D2 of the needle and the diameter D3 of the nozzle pin. The stroke H of the nozzle needle is limited by the clearance of a shoulder 13 of the nozzle needle from the front surface 14 of the nozzle holder.

The injection pin has a cylindrical section with a diameter D3 and a tapering conical section connected thereto. The length of the cylindrical section is so proportioned that its depth of penetration into the injection aperture 12 is about the same as half the needle stroke when the needle nozzle is closed (Figs. 2, 4, 6). The overall length of the nozzle pin is so selected that the pin is completely extracted from the cylindrical injection aperture when the needle is completely raised (Figs. 3, 5 and 7).

The three examples of construction differ from each other substantially only by the length of the cylindrical injection aperture 12. With the rst example of construction as shown in Figs. l to 3, the pin projects with its conical section above the lower front surface of the nozzle body l when the nozzle needle is closed. The length of the cylindrical injection aperture is about 0.5 times the size of its diameter. In the second examples, as shown in Figs. 4 and 5, the end of the nozzle pin and the lower front surface of the nozzle body are disposed in one plane when the nozzle needle is closed. ln a third example, as shown in Figs. 6 and 7, the pin penetrates, when the nozzle needle is closed, only up to the middle of the cylindrical injection aperture therein. The length of the cylindrical nozzle aperture is in this case about twice as large as its diameter.

When injecting minor amounts of fuel, as happens with no load and under light loading conditions, the nozzle needle does not rise completely, so that the pin remains penetrated into the injection aperture; the nozzle thus acts as a pin nozzle and in doing so yields a loose hollow stream. When injecting large amounts of fuel, as happens in the region of full load and upper part load region, the fuel pressure completely raises the nozzle needle, so that the nozzle acts in this case as a hole nozzle on account of its small injection hole diameter of 0.9 mm. at the most, and therefore yields a rigid fully closed stream.

If, at the same time, a closing spring 4 is provided, the force of which increases more powerfully, in the known manner, during the first part of the needle stroke until, therefore, the cylindrical section of the pin 11 penetrates into the injection aperture, than the force of the fuel pressure engaging in the opening direction on the needle and likewise increasing owing to the needle shoulders (D2 D3) becoming active at the same time in addition, a ltind of preliminary injection is obtained by throttling the outlet cross section over the ignition delay time, which allows for a smooth running of the engine.

I claim:

l. A fuel injection nozzle for internal combustion engines, including in combination a needle body, a nozzle needle, a pin on the end of said needle on the injection side which penetrates into a cylindrical aperture of the needle body of less than 0.9 millimetre diameter, with free spacing therein, to act during the initial part of its stroke as a pin nozzle, and during the latter part of its stroke as a hole nozzle, and a closing spring acting on said nozzle needle, said pin including a cylindrical section contiguous with the nozzle needle and a conical inwardly tapering free end section on the cylindrical section, the depth of penetration of the said cylindrical section into said aperture being substantially one half of the needle stroke when the nozzle needle is closed.

2. A fuel injection nozzle for internal combustion engines, including in combination a needle body, a nozzle needle, a pin on the end of said needle on the injection Side which penetrates into a cylindrical aperture of the needle body of less than 0.9 millimetre diameter, with free spacing therein, to act during the initial part of its stroke as a pin nozzle, and during the latter part of its stroke as a hole nozzle, and a closing spring acting on said nozzle needle, said pin including a cylindrical section contiguous with the nozzle needle and a conical inwardly tapering free end section on the cylindrical section, the depth of penetration of said cylindrical section into said aperture being substantially one half of the needle stroke when the nozzle needle is closed and the length of the said cylindrical aperture between one half and twice its diameter.

References Cited inthe le of this patent UNlTED STATES PATENTS 2,017,028 Heinrich Oct. 8, 1935 2,020,144 Howell Nov. 5, 1935 FOREIGN PATENTS 452,899 Germany Nov. 23, 1927 779,909 France Ian. 24, 1935 788,909 France Aug. 5, 1935 837,337 Germany Apr. 21, 1952 

